Powered roller mechanism

ABSTRACT

A powered roller movable laterally of its axis between a retracted position and an advanced position is unitary with the ring gear of an eccentric planetary gear set having a sun gear input. The ring gear is journalled on the planet gear carrier eccentrically thereof for movement thereby along an orbit between the two positions of the roller.

nited States Patent 1191 McKee Jan. 23, 1973 POWERED ROLLER MECHANISM[75] Inventor: James E. McKee, Goleta, Calif.

[73] Assignees: Republic National Bank of Dallas;

Irving Trust Company; Union Bank [22] Filed: Feb. 19, 1971 21 Appl.No.:117,125

Related U.S. Application Data [63] Continuation of Ser. No. 865,071,Oct. 9, i969,

abandoned.

[52] U.S. Cl. ..l98/127 R [51] Int. Cl. ..B65g 13/02 [58] Field ofSearch ..l98/l27; 214/84; 244/137 [56] References Cited UNITED STATESPATENTS 3,447,665 6/1969 Egeland ..2i4/84 X 3,568,821 3/1971 Gronkuist..l98/127 R Primary ExaminerEdward A. Sroka Attorney-Smyth, Roston &Pavitt [5 7} ABSTRACT A powered roller movable laterally of its axisbetween a retracted position and an advanced position is unitary withthe ring gear of an eccentric planetary gear set having a sun gearinput. The ring gear is journalled on the planet gear carriereccentrically thereof for movement thereby along an orbit between thetwo positions of the roller.

23 Claims, 16 Drawing Figures PATENTEI] M2 7 3,712,454

SHEET 10F 5 Gin/145$ MCSKEE PAIENTEDJAHZEI I973 I 3,712,454

SHEET 5 BF 5 OOGOOOOO 52 o o o o 0 7? fire/J2.

JM Eyme.

POWERED ROLLER MECHANISM This application is a continuation of U.S.application Ser. No. 865,071, filed Oct. 9, 1969 and now abandoned.

BACKGROUND OF THE INVENTION For a number of widely different purposes itis useful to rotate a rotary body and to shift the rotary body on a pathtransversely of its axis from a retracted position to one or moreadvanced positions. For example, the rotary body may be a grinding wheelwhich is advanced towards a workpiece that is to be processed.

The invention has special utility in the form of a powered roller thatis normally retracted below a support plane and, when desired, isadvanced upward for tangential contact with the bottom surfaces ofobjects to move the objects along the support plane. The initialembodiment of the invention is employed in this manner to shift heavycargo items along the cargo space of a vehicle such as a jet aircraft.The description herein of this initial embodiment will provide adequateguidance for persons skilled in the art who may have occasion to applythe underlying concept of the invention to other specific purposes.

The cargo space of an airplane is commonly provided with built-in freelyrotatable support elements in the form of balls and rollers which definea support plane for palletized or containerized cargo items and whichminimize frictional resistance to movement of the cargo items along thesupport plane. For the purpose'of illustration, the invention will bedescribed as applied to such a builtin structure of the characterdisclosed in the Davidson U.S. Pat. No. 3,262,588 issued July 26, 1966,whichprior disclosure is hereby incorporated into the present disclosureby reference.

in the Davidson disclosure, the floor of the cargo space that isopposite the side door of the aircraft is provided with a ball mat, theuniversally rotatable balls of which define a support plane and serve tominimize frictional resistance to movement of cargo items from thedoorway onto the door mat as well as to minimize frictional resistanceto direction change of the cargo items and initial movement of the cargoitems longitudinally of the aircraft. The areas of the floor space thatextend in both longitudinal directions from the ball mat are providedwith rotatable support elements in the form of rollers having their axisperpendicular to the longitudinal axis of the aircraft, the rollersbeing mounted on so-called trays that are releasably anchored to seatrails in longitudinal alignment with the aircraft.

The described arrangement of ball mats and roller trays greatlyfacilitates stowing cargo units in the aircraft but neverthelessphysical effort and appreciabletime is required to push a cargo itemfrom the region of the side door to thecentral area of the ball mat andthen to transfer the cargo unit to the roller trays for movementlongitudinally of the aircraft. Usually at least five men are requiredto load or unload av large: cargo aircraft in 30 to -40 minutes and,based on an average load per aircraft today of 58,000 pounds, only 11planes a day can be loaded or unloaded by acargohandling crew. It isalso to be noted that serious hazards to the cargo handlers are involvedin such a manual operation.

With the era approaching of jet aircraft such as the Boeing 747 and theLockheed L-l0ll of greatly increased cargo capacity and correspondinglyincreased fixed costs, concerted efforts are now being made to meet theneed for more nearly automated cargo handling methods involving poweredmeans incorporated in the structure of the cargo space to move cargoitems under more or less remote control. A primary object of the presentinvention is to meet the various problems involved in satisfying thisneed and thus make it possible for one man, or at most two men, to load100,000 pounds of cargo or more into a large aircraft in 20 minutes orless.

It has been determined that the new requirements may be met by providingthe cargo space of the aircraft with suitably constructed reversiblepowered rollers to cooperate both with the universally rotatable ballsof the ball mats and with the rollers of the longitudinal roller trays,provided that the powered rollers are shiftable by remote control fromretracted positions out of the way below the support plane of the cargospace'to upper positions at which the powered rollers protrude above thesupport plane for tangential traction contact with the bottom surfacesof the cargo items.

For example, a pair of reversible retractable power rollers with theiraxis parallel with the aircraft axis may propel cargo items from theregion of the side door a desired distance across the ball mat where apowered roller with its axis perpendicular to the longitudinal axis ofthe aircraft may take over to initiate movement of the cargo items ineither direction longitudinally of the aircraft away from the entrancearea. A third powered roller of the same orientation. as the secondpowered roller may complete the longitudinal travel of cargo items fromthe ball mat into the short bay forward of theside'door and successivesimilarly oriented powered rollers may successively engage cargo itemsto propel the items longitudinally of the aircraft any required distancetowards the rear end of the cargo space.

The specific objects of the presently preferred embodiment of theinvention include the following: to provide a reversible powered rollerunit that is compact enough to fitinto the shallow space between thecargo support plane and the floor of the aircraft and yet is powerfulenough to propel a cargo item weighing up to 13,500 or more pounds at arate, for example of feet per minute; to make such a powered roller unitsubstantially immune to impact damage by portions of cargo items that.may sag below the support plane; to provide sufficient power to move theheaviest cargo itern-andat the. same time safeguard the powered rollermechanism from damaging stress in the event that movement of .the cargoitem is abruptly blocked while therolleris energized; to provideefficient means to raiseand lower the powered roller under remotecontrol with minimal addition of structure required to raise and, lowerthe roller and without complicating theremote control, only one signalbeing requiredboth to cause energization and raising of the roller or tocause mediately adjacent a cargo item when a powered roller is energizedto propel the cargo item.

3 SUMMARY OF THE INVENTION As will be explained more fully, theinvention takes advantage of the unique and highly advantageousgeometrical behavior of what may be termed an eccentric planetary geartrain comprising: an input sun gear; a planet gear carrier with its axisof rotation concentric to the sun gear; a ring gear mounted on thecarrier ec-' centrically thereof, i.e., with its axis of rotation offsetfrom the common axis of rotation of the carrier and sun gear; and aplanet gear journalled on the carrier in mesh with both the sun gear andthe ring gear. Such a planetary gear train may be adapted to the purposeof the present invention by simply making the cargo- .propelling rollerunitary with the ring gear. Preferably the ring gear is a cylindricalmember of substantially approximately the same axial dimension as thepropelling roller with the propelling roller encasing the ring gear andwith the carrier axially elongated to extend beyond both ends of thecylindrical ring gear for effective support of the propelling roller.

A basic advantage of such an arrangement is that rotation of the planetgear carrier moves the propelling roller in an orbit between a retractedposition below the cargo support plane and an upper position protrudingsufficiently above the support plane for effective traction contactagainst the bottom surface of a cargo unit. With the planet gearcooperative with the sun gear effective to reversibly rotate thepropelling roller on its axis at any orbital position of the propellingroller, the only further actuation requirements are rotation of thecarrier to raise and lower the propelling roller and when the propellingroller reaches its upper position. In

the present embodiment of the invention both latches are carried, by areciprocative yoke which is spring biased in one direction and isoperable by solenoid means in the opposite direction.

releasable immobilization of the carrier at the elevated position of thepropelling roller.

Within the scope of the invention various means may be provided torotate and releasably immobilize the carrier. For example a second powerinput in addition to the sun gear may be provided to rotate the carrierdirectly under remote control. A feature of the preferred practice ofthe invention, however, is the concept of using the sun gear as the solepower input and of diverting at least a portion of the power flowtemporarily to rotate the carrier when required for raising and loweringthe propelling roller. In this regard an important feature of thepresent embodiment of the invention is the further concept offrictionally coupling the planet gear carrier and the ring gear toprovide the required diversion of the power flow.

The friction coupling causes rotation of the planet gear carrierwhenever energization of the sun gear is initiated in either rotarydirection and the invention provides a first latch to immobilize thecarrier automatically when the cargo-propelling roller rises to itseffective upper position. Subsequent deenergization of the latch tounlatch the carrier to permit the sun gear to rotate the carrier tolower the cargo-propelling roller to its retracted position whereupon asecond latch automatically immobilizes the carrier to keep the rollerretracted.

In the preferred embodiment of the invention this automatic dual latchconcept is carried out by forming the carrier with a surface concentricto its axis of rotation with a suitable latch recess therein that isengaged by the first latch when the propelling roller is elevated and isengaged by the second latch when rotation of the carrier retracts thepropeller roller. With the first latch spring biased away from thecarrier and the Other features of the invention include: theincorporation of a motor in the powered roller unit to energize the sungear; the further incorporation of reduction gearing of the planetarytype; the combination with the planetary reduction gearing of torquelimiter means; the provision of a switch mechanically operated by asolenoid-actuated latch for the planet gear carrier, which switchenergizes the motor whenever the latch releases the carrier at the lowerretracted position of the cargo-propelling roller; the provision of acontrol.

switch with a push button to energize the latch solenoid as long as thepush button is depressed with the further provision of delay means toprolong the energization of the motor for a predetennined number ofseconds after the push button is released; the provision of simplefriction means to couple the carrier and ring gear; and the shaping ,ofthe housing of the powered roller item with inclined marginal surfacesto minimize input damage to the item by sagging portions of cargo items.

The various features and advantages of the invention may be understoodby reference to the following detailed description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to beregarded as merely illustrative: I

FIG. 1 is a diagrammatic view to explain the geometrical behavior ofwhat may be termed an eccentric planetary gear train that is a basicfeature of the invention;

FIG. 2 is a diagram showing a cargo-propelling roller encasing the ringgear and showing two latches controlled by a solenoid and a cooperatingspring, the mechanism being shown at the normal lower position of thecargo-propelling roller with the solenoid deenergized;

FIG. 3 is a view similar to FIG. 2 with the powered roller atits upperposition to propel a cargo item, the solenoid being energized;

FIG. 4 is a view similar to FIG. 3 showing the solenoid deenergized topermit the cargo-propelling roller to return to its normal lowerposition;

FIG. 4a is a diagrammatic view of a modification wherein retarding meansacting externally on the roller causes the roller to be elevated whenthe sun gear is energized;

FIG. 5 is a plan view of the presently preferred embodiment of theinvention with parts broken away;

FIG. 6 is a longitudinal sectional view of a longitudinal portion of thestructure shown in FIG. 5;

FIG. 7 is a longitudinal sectional view on a different plane showing therest of the structure;

FIG. 8 is a plan view of the latch yoke;

FIG. 9 is a side elevational view of the yoke;

FIG. 10 is an end elevation on reduced scale of the structure shown inFIG. 5;

FIG. 10a is a fragmentary view in side elevation of an alternate form ofa torque limiter that may be employed;

FIG. 11 is a fragmentary diagrammatic plan view of the cargo space of anaircraft;

FIG. 12 is a wiring diagram of a control circuit for a propeller rollerunit;

FIG. 13 is a diagrammatic side elevational view illustrating how theprinciples of the invention may be embodied in means to drive and shifta grinding wheel; and

FIG. 14 is a view taken along the line 14-14 of FIG. 13 showing means toindicate the advance of the grinding wheel.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION BASIC MODE OFOPERATION FIG. 1 shows what may be termed an eccentric planetary geartrain that is a basic feature of the invention. The gear train includesan input sun gear 20, a planet gear carrier 22 with its axis of rotationconcentric to the sun gear, a ring gear 24 and a planet gear 25 that isin mesh both with the sun gear and the ring gear. The planetary geartrain is eccentric in the-sense that the ring gear 24 is journalled onthe planet gear carrier 22 for rotation on an eccentric axis 26, theaxis 26 being offset from the common axis of rotation 28 of the sun gearand planet gear carrier. It is apparent that rotation of the carrier 22on the axis 28 moves the axis 26 of the ring gear in a circular orbit.In FIG. 1 the ring gear is at the top of its'orbit with its axis 26 atthe point designated 26. When the ring gear is at its opposite positionat the bottom of its orbit its axis is at the point designated 30 inFIG. 1.

If the carrier 22 is immobilized by any given orbital position of thering gear 24, power flows from the input. sun gear through the planetgear 25 to the ring gear to Thus power from the sun gear 20 may flow tothe ring gear alone to cause rotation of the ring gear at whateverdegree of elevation the ring gear may be or the power flow may bediverted to the carrier 22 whenever it is desired to change theelevation of the ring gear. his to be understood, however, that withinthe-scope of the invention instead of diverting power flow from the sungear to the carrier '22 to raise and lower the ring'geana second powerinput may be applied directly to the carrier to raise and lower the ringgear.

FIG. 2 shows how the underlying concept of aneccentric planetary. geartrain is incorporated in the presently preferred embodiment of theinvention. In the construction represented by FIG. 2, the ring gear 24is an elongated cylinder and a cargo-moving roller, generally designated32, is in the form of a cylinder that fixedly encases the ringgearcylinder. The roller may be equipped with a suitable coating 34 ofplastic, for example polyurethane, for frictional contact with thecargo. The carrier 22 is of circular peripheral configuration with asingle latch recess 35 for cooperation alternately with a first latch 36and a second latch 38, the two latches being unitary parts of areciprocative yoke 40. In FIG. 2 the roller 32 is in its normal positionat the bottom of its orbit and the yoke 40 is in its normal positionbiased to the right by a spring 42 to bias the first latch 36 away fromthe carrier 22 and to holdthe second latch 36 in engagement with thelatch recess 35 to immobilize the carrier but the bias of the yoke maybe reversed by a solenoid 44.

In the preferred embodiment of the invention, rotation of the carrier 22to raise and lower the roller 32 is accomplished by frictionallycoupling two components of the planetary gearing. For this purpose thedouble arrow 45 in FIGS. 2-4 represents frictional means effectivebetween the ring gear 24 and the carrier 22 to yieldingly lock up theplanetary gear train for rotation as a unit, the friction means actingspecifically between the roller 32 and the carrier.

In the preferred practice of the invention the solenoid 44 is energizedin time relation to energization of the motor that drives the sun gear20 and for this purpose, the motor is controlledby a switch 46 shown inFIGS. 2-4 which is responsive to the shifting of the latch yoke 40. Theswitch 46 is normally closed and is in its normally closed state in FIG.2. The latch yoke 40 is shown in solid lines at its right limit positionin FIG. 2 and the dotted lines in FIG. 2 indicate an intermediateposition of the switch at which the latch 36 presses against theperiphery of the carrier 22, the latch recess 35 being remote from thelatch 36. FIG. 4 shows the latch yoke at another intermediate positionat which the solenoid 44 is deenergized and the spring 42 urges thelatch 38 against the arcuate periphery of the carrier 22. FIG. 3 showsthe roller 32 at its upper position with the latch yoke at its leftlimit position. The switch 46 that controls the motor is normally openand is open in FIG. 2, where the latch yoke is at its right limitposition. Atall other positions of the latch yoke, including theintermediate position indicated by dotted lines in FIG. 2 and theintermediate position shown in FIG. 4,.the switch 46 is closed toenergize the motor. Thus the switch 46 is closed at all positions of thelatch yoke 40 except the right limit position shown in FIG. 2.

The operating cycle is as follows: Starting with the parts intheirnormal positions shown in FIG. 2, the motor and the solenoid beingdeenergized and the cargo-propelling roller 32 being at its normal lowerretracted position, the latch 38 is in engagement with the latch recess35 to immobilize the carrier 22 and the latch 36 is retracted. When thesolenoid 44 is energized by a control signal the latch yoke 40 isshifted leftward from itsnormal position to an intermediate positionindicated by dotted-lines in FIG. 2 where the latch 36 presses againstthe arcuate periphery of the carrier 22. This initial leftward shift ofthe latch yoke 40 closes the switch 46 to actuate the sun gear 20,whereupon the carrier 22 rotates 180 by virtue .of the frictionalcoupling of the carrier and the ring gear. With the solenoid'pulling thelatch 36 against the periphery of the carrier 22, the latch 36 snapsinto engagement with the latch recess 35-at theend of the 180 ofrotation of the carrier to immobilize the carrier as shown in FIG. 3withthe cargo-propelling roller 32 at its elevated position. In effect,the frictional coupling between the ring gear and the carrier locks upthe planetary gear train to carry out the l of rotation of the carrier.

When the control signal is subsequently removed with the parts in thepositions shown in FIG. 3, the latch yoke 40 is shifted rightward by thespring 42 to cause the latch 36 to release the carrier 22 and to causethe latch 38 to press against the periphery of the carrier as shown inFIG. 4. Switch 46 remains closed for continued energization of the motoruntil another 180 of rotation of the carrier 22 is completed to permitthe latch 38 to seat again in the latch recess to immobilize the carrier22 with the cargo-propelling roller at its normal retracted position.The final shift of the latch yoke 40 rightward from the position shownin FIG. 4 to the normal position shown in FIG. 2 opens the switch 46 todeenergize the motor with the cargo-propelling roller 32 at its lowerretracted position.

If the ring gear 24 with the roller 32 fixedly mounted thereon is heldagainst rotation while the sun gear 20 is energized, the carrier 22 willrotate to move the nonrotating roller in a rotary path. It is apparent,therefore, that instead of frictionally coupling the carrier and thering gear to change the elevation of the roller 32, simple frictionalbrake means may be applied directly to the roller.

FIG. 4a shows how such a brake means in the form of a leaf spring 47 maybe mounted below the roller 32 to exert upward pressure against theunderside of the roller when the roller is atits lower retractedposition. The range of resilient flexure of the leaf spring 46 issufficient to follow the upward movement of the. roller from itsretracted position until the roller makes initial frictional contactwith a cargo item whereupon the cargo item takes over the function ofretarding the roller. The roller 32 then completes its upward movementto its upper limit position to lift the cargo item and, preferably, indoing so moves out of the range of the leaf spring. If desired, anequivalent of the leaf spring may be employed in the form of aresilient-body of elastomeric material, such as a suitable foamedplastic.

STRUCTURAL DETAILS OF THE PREFERRED EMBODIMENT Turning now to thespecific structure of the presently preferred embodiment of theinvention and referring first to FIGS. 6 and 7, a motor, generallydesignated 50, has a shaft 52 which is journalled in bearings 54 and, bymeans which will be described later, the shaft is operatively connectedto a first spur gear 55 near the right end of FIG. 6. The first spurgear 55 in turn meshes with a second spur gear 56 shown near the leftend of FIG. 7 which is keyed to a shaft 58 that is journalled inbearings 60. The shaft 58 carries an axially elongated previouslymentioned sun gear 20 inside the cargopropelling roller 32.

Rotatably mounted on the sun gear shaft 58 by bearings 62 is thepreviously mentioned planet gear carrier 22 which is axially elongatedand carries a pair of coaxial planet gears which comprise the previouslymentioned planet gear 25. The planet gears 25 are mounted by bearings asshown in individual stub shafts 64. The planet gear carrier 22 has aneccentric outer peripheral surface of cylindrical cross section on whichthe previously mentioned ring gear 24 is mounted by bearings 64, thering gear being of the configuration of an axially elongated cylinder.Thus the ring gear 24 rotates on an axis that is offset from the commonaxis of corresponding O-rings 68 in peripheral contact with the carrier22.

For the purpose of frictionally coupling the ring gear 24 and thecarrier 22, a collar 70 mounted on the carrier and secured thereto by aradial screw 72 cooperates with a circumferential wafer spring 74 ofundulating configuration which is confined under light stress betweenthe collar 70 and the previously mentioned intemal ring 65 of thecargo-propelling roller 32. Thus the wafer spring is effective to lockup the planetary gear train in a yielding manner to cause orbitalmovement of the cargo propelling roller 32.

In the construction shown, the motor 50 and associated components foractuating the sun gear 20 are enclosed in a low profile housing 75 withthe sun gear and the carrier extending beyond one end of the housing asshown in FIGS. 5 and 7. As best shown in FIG. 5, a unitary part of thehousing 75 is a guard 76 that extends around the opposite sides andouter end of the cargo-propelling roller 32, the purpose of the guardbeing to protect the roller and especially so at the lower retractedposition of the roller. The guard 76 also serves to support outerbearing 60 of the sun gear shaft As shown in FIGS. 6, 7 and 10, both theupper portion of the housing 75 and the upper portion of the guard 76are of what may be termed a chamfered configuration having inclinedmarginal surfaces 78. These inclinedmarginal surfaces 78 serve to wardoff or cam upwardly any sagging portion of a cargo unit that may tend tomake impact against the housing or guard. FIG. 10 shows the range oftranslation of the cargopropelling roller 32 between a lower limitposition 80 within the boundaries of the housing 75 and an upper limitposition 82 at which the roller protrudes sufficiently above the housingto make effective traction contact with cargo items.

The means to operatively connect the motor shaft 52 to the spur gear 55may comprise reduction gearing in the form of two stages of planetarygearing. In the first stage a sun gear 84 on the motor shaft '52 mesheswith first stage planet gears 85 which are mounted on a first stageplanet gear carrier 86. The planet'gears 85 mesh with both the firststage sun gear 84 and a first stage ring gear 88. The first stage planetgear carrier 86 is fixedly mounted on a stub shaft 90 which carries asecond stage sun gear 92..The second stage sun gear meshes with secondstage planet gears 94 which in turn mesh with a second stage ring gear95. The second stage planet gears 94 are mounted on a second stageplanet gear carrier 96 which is keyed to a stub shaft 98 that isjournalled in bearings 100 and carries the previously mentioned firstspur gear 55.

The two stages of planetary gearing reduces the peripheral speed of thecargo-shifting roller 32 to a suitable rate, which may be approximately60 feet per minute.

The use of planetary gears for reduction gearing is advantageous in thatit permits the combination with the reduction gearing of a torquelimiter to protect the mechanism in the event that a cargo item underpropulsion by the cargo roller 32 is blocked with consequent abrupt risein stressing of the parts of the mechanism. For this purpose, the firststage ring gear 88 is mounted on bearings 103 and suitable frictionmeans resists rotation of the ring gear.

In the present embodiment of the invention, as shown in FIGS. and 6, thefrictional torque limiting means comprises a pair of arcuate frictionshoes 104 which are interconnected by a fixed pivot 105 and areinterconnected at their confronting outer ends by means including ascrew 106 which provides for adjustment of the pressure with which theshoes grip the ring gear 88. The magnitude 'of the torque that isresisted by the friction shoes is above the nonnal torque output of themotor but is below the torque output augmented by inertia of the motor.When a cargo item being shifted by the roller 32 is suddenly obstructed,the consequent abrupt rise in torque resistance results first indissipation of power by the friction shoesand then stalling of themotor.

It is to be understood, of course, that any suitable torque limiter maybe used within the scope of the invention. For example, with the firststage ring gear 88 permanently immobilized, the stub shaft 98 may bemade in two sections 98a and 98b as shown in FIG. a and the two sectionsmay be yieldingly interconnected by a conventional adjustable frictionclutch 108.

The construction of the previously mentioned yoke that carries thepreviously mentioned first and second latches 36, 38 may be understoodby referring to FIGS. 5, 6, 8 and 9. As shown in FIGS. 8 and 9 the yoke40 has a full-length side plate 110 and two longitudinally spacedshorter opposite side plates 112 and 114. The'short side plate 1 12 isconnected to the longer side plate 110 by a pair of studs 115 whichcarry corresponding antifriction rollers 117 for cooperation withcorresponding fixed upper and lower guide plates 118 shown in FIG. 6. Athird stud 119 carries a roller 36 which is the previously mentionedfirst latch 36. The short side plate 114 is connected to the longer sideplate 110 by screws 120 that pass through a spacer block 121 and by apair of studs 122 that carry corresponding" anti-friction rollers 123.The previously mentioned second latch 38 is a projection of the spacerblock 121 between the side plates 110 and 114. The yoke 20 slides on thefour anti-friction rollers 117, 123 along the guideway that is formed byguide plates 1 l8.

- To cooperate with the first latch 36 and the second latch 38, theplanet gear carrier 22 is fixedly embraced by a sleeve 125 (FIG. 7) withan integral collar 126 that is anchored to the carrier by a radial screw128. The outer circumferential surface of the collar 126 isconcentric tothe axis of rotation of the carrier 22 and, as shown in phantom in FIG.9, the collar is fonned with the previously described latching recess 35of the carrier.

As shown in FIG. 5, the mechanism for controlling the yoke 40 comprisesthe previously mentioned solenoid 44 which has anarmature 130 slidinglymounted in a slide bearing 132. The armature 130 is connected by a pivot134 to one arm of a bellcrank 135 that is rotatable about a fixed pivot136. The second arm 138 of the bellcrank extends into a circularaperture 140 of the long side plate 110. As indicated in FIG. 8 thecircular aperture 140 may be provided with a bushing 142. The second arm138 of the bellcrank 135 carries a roller 144 for rolling contact withthe bushing 142 to control reciprocation of the yoke 40.

To bias the yoke 40 towards its normal limit position a coil spring 42which is the previously mentioned spring 42 embraces the armature 130under compression between the body of the solenoid 144 and a collar 145that is fixedly mounted on the armature. Thus when the armature isdeenergized, the spring 42 is expanded as shown in FIG. 5 to cause thebellcrank 35 to be urged clockwise to hold the yoke 40 in its normalposition which is towards the bottom of FIG. 5. At this normal positionof the yoke, the pressure of the spring 42 urges the second latch 38into the latch seat 35 as previously described in reference to FIG. 2.0n the other hand, when the solenoid is energized, the second latch 38is retracted and the first latch 35 is advanced towards the collar 126of the planetgear carrier as heretofore described. It is apparent thatthe two latches are effective for carrying out the operating cycleregardless of the direction in which the carrier 22 is rotated.

A suitable control circuit for a cargo-shifting unit of the describedconstruction is shown in FIG. 12 wherein a switch 146 operated by a pushbutton 147 closes a direct current circuit 148 to energize thepreviously mentioned solenoid 44 which, as previously described,mechanically operates the previously described switch 46, and the switch46 in turn controls a relay 152 for energization of the motor 50. Theswitch 146 energizes the solenoid 44 as long as the push button 147 isdepressed'and incorporates a time delay to keep the solenoid energizedfor a few seconds after the push button is released. Thus the pushbutton may be momentarily depressed to cause a cargo item to bepropelled a few feet. The four leads 154 that terminate at the motor areconnected to a reversing relay 155. A toggle switch 156 which may beshifted in opposite directions causes opposite rotations of the motor50. The push button switch 146 and the toggle switch 156 for thereversing switch are mounted on the same control panel. FIG. 11 showssuch a control panel 158 that is pendant on a control cable 159 andfurther shows a similar fixed control panel 160. The pendant controlpanel 158 may be moved into and out of the cargo space and may be hungon the wall in the cargo space when not is use.

FIG. 11 shows diagrammatically how the cargo space of an aircraft may beprovided with structure of the character disclosed in the Davidsonpatent, the structure including a set of ball mats 162 in the areaopposite the side door opening 164 of the aircraft and further includinglongitudinal roller trays 165 to move cargo from the ball mats to thefront bay of the'cargo space and additional roller trays 166 tofacilitate movement of cargo forwardly from the ball mat area.

By way of example of how the present invention may be applied to thestructure shown in FIG. 12, a first pair of coaxial poweredcargo-propelling rollers 32a are positioned near the doorway 164 tocooperate with the ball elements 168 of the ball mat area to advancecargo items fromthe doorway into the central portion of the ball matarea. The ball mat area further includes two power actuatedcargo-propelling rollers 32b with their axis perpendicular to the axisof the aircraft to cooperate with the ball elements 168 to shift cargoitems either forward to the roller trays 165 or rearward to the rollertrays 166. The forward bay which is provided with the roller trays 165has a power-actuated cargo-propelling roller 32c to complete thetransfer of cargo items from the ball mat area to the bay.

The rearwardly extending portion of the cargo area is provided with asuccession of spaced cargo-propelling rollers 32d, 32e, 32f, etc. tocooperate with the roller trays 166, the successive cargo-propellingrollers being effective in sequence to shift cargo items as far rearwardas required. The rectangle 170 with diagonals represents a cargo itemstowed in the forward bay and the similar rectangle 171 represents acargo item in route to the rear end of the cargo space. The controlpanel 160 that is mounted at a suitable location adjacent the doorway164 may have two switches, namely a reversing switch to determine thedirection of rotation of all of the various cargo-propelling rollers, apush button to control energization of the cargo-propelling rollers 32!;and 32c. The pendant panel 158 may also have two switches, namely, aswitch to energize the cargo-propelling roller 32a and a switch toenergize the cargo-propelling roller 32b, roller 32b being controlled byeither panel. After a foot switch 132d has been operated to energizeroller 32d to advance a cargo item rearwardly of the aircraft to thelimit of, the range of cargo-propelling roller 32d, the operator maywalk into the cargo space and depress a foot switch l72e to energize thecargo-propelling roller 322. In like manner a foot.switch l72f controlsthe cargo-propelling roller 32f and a foot switch 172g controls the nextcargo shifting roller (not shown) etc. It is to be noted that the footswitches are safely remote from the cargo-propelling rollers that theycontrol. The described procedure is safe because the operator is alwaysto the rear of any cargo item that is moving under power.

OTHER APPLICATIONS OF THE INVENTION By way of example of another use forthe underlying concept of the invention, FIG. 13 shows a grinding wheel175 which may be incrementally advanced towards, a workpiece 176 that isreciprocated as indicated by the double arrow 178. The mechanism fordriving the grinding wheel on its axis and for shifting the grindingwheel incrementally towards the workpiece 176 comprises the previouslydescribed eccentric planetary gear train which includes a planet gearcarrier 22a. The planet gear carrier 22a is in the fonn of a worm gearthat is controlled by a worm 180 on a control shaft 182. The outer endof the control shaft hasra disk 184 provided with a crank 185 for manualrotation of the control shaft. Suitable means to indicate precisely thedegree to which the grinding wheel is advanced partures from mydisclosure within the scope of the invention.

I claim:

1. In a cargo handling system for a cargo carrier wherein a plurality ofdistributed support elements support cargo items at a support plane andare rotatable to minimize frictional resistance to movement of the cargoitems along the plane and a plurality of power-actuated rollers areshiftable from lower positions below said plane to upper positionsprotruding above the plane to engage the bottoms of the cargo items tocooperate with the rotatable support elements to move the cargo itemsalong the support plane,

the improvement comprising each of said rollers being a working part ofa corresponding powered unit, said powered unit including:

an input sun gear;

reversible means to actuate the sun gear;

a planet gear carrier with its axis of rotation concentric with the sungear;

a ring gear unitary with the roller coaxially thereof,

said ring gear being rotatably mounted on the carrier with its axis ofrotation offset from the axis of the carrier to cause rotation of thecarrier to move the roller in an orbit between its lower position andits upper position;

planet gear means on the carrier in mesh with both the sun gear and thering gear; and

means to rotate the carrier for orbital movement of the roller.

2. An improvement as set forth in claim 1 which includes means toreleasably immobilize the carrier at the upper position of the roller.

3. An improvement as set forth in claim I in which said ring gear is ofcylindrical configuration and is united with the roller inside theroller;

and in which said sun gear, said carrier and said planet. gear means allextend longitudinally of the roller inside the roller.

4. An improvement as set forth in claim 1 in which said planet gearmeans includes at least one pair of axially spaced coaxial planet gears.

5. An improvement as set forth in claim 1 in which said reversible meansto actuate the sun gear is a motor;

which includes a remote switch to control energization of the motor;

and which includes remote means to control the direction of rotation ofthe motor.

6. An improvement as set forth in claim 5 in which said remote switchcreates a signal to energize the motor and incorporates means to delayde-energization of the motor when the remote switch is operated.

7. An improvement as set forth in claim 1 which includes means to limitthe torque transmitted to the sun gear to a given magnitude above themagnitude of the normal driving torque of the motor but below adestructive magnitude in the event that the movement of a cargo item isblocked while the motor is energized.

8. An improvement as set forth in claim 4 which includes reductiongearing to transmit torque to the sun gear and in which said torquelimiting means is combined with the reduction gearing.

9. An improvement as set forth in claim 8 in which the reduction gearingincludes a planetary gear train comprising a sun gear, a planet gearcarrier, a ring gear and a planet gear on the carrier in mesh with boththe sun gear and the ring gear;

and in which the torque limiting means frictionally opposes rotation ofthe ring gear of the reduction gearing.

1 0. An improvement as set forth in claim 1 which includes means tocause power flow from the sun gear to the planet gear carrier to rotatethe planet gear carrier to shift the roller between its lower and upperpositions.

11. An improvement as set forth in claim which includes means responsiveto energization of the sun gear to latch the carrier in response tomovement of the roller to its upper position and to release the carrierin response to deenergization of the sun gear to permit the momentum ofthe rotating parts to rotate the carrier to shift the roller from itsupper position to its lower position.

12. An improvement as set forth in claim 11 which includes a secondlatch biased to latch the carrier in response to rotation of the carrierat the lower position of the roller after the motor is de-energized,said second latch being releasable in response to energization of themotor.

13. An improvement as set forth in claim 11 which includes a housingenclosing moving parts of the unit;

and in which the portions of the sun gear and the carrier protrude tothe exterior of the housing with the ring gear mounted on the protrudingportion of the carrier and with the roller encasing the ring gear.

14. An improvement as set forth in claim 10 in which the upper portionof the housing is of chamfered configuration to minimize head-on impactagainst the housing of cargo items that protrude downwardly from saidplane.

15. An improvement as set forth in claim 12 which includes guard meansbelow said plane adjacent the roller to protect the roller at the lowerposition of the roller.

16. An improvement as set forth in claim 15 in which the upper portionof the guard means is of chamfered configuration to minimize head-onimpact against the guard means of cargo items that protrude downwardlyfrom said plane.

17. An improvement as set forth in claim 1 in which the floor of thecargo carrier is equipped with seat rails;

in which said unit has two longitudinally spaced means for releasableattaching the unit to a seat rail longitudinally thereof;

and in which said unit has two laterally spaced means for releasableattachment to a seat rail with the unit positioned transversely of theseat rail. 18. In a system for handling objects such as cargo items,wherein the system includes support structure of open construction tosupport the objects at a support plane,

the combination therewith of: at least one roller movable bodily throughthe open support structure between a retracted position below said planeand an effective position protruding above the plane to engage thebottoms of the objects to move the objects across the support structure;c

a single drive means to power the roller; and

control means operable in a first respect to cause the drive means toshift the roller between its two positions and operable in a secondrespect to operatively connect the drive means to the roller to rotatethe roller on its axis when the roller is in its effective position.

19. A combination as set forth in claim 18 in which the roller is hollowwith inner circumferential gear teeth;

in which drive means extends from the power means into theinterior ofthe roller;

which includes means responsive to the operation of the control means inits first respect to cause said drive means to shift the roller betweenits two positions; and which includes means responsive to operation ofthe control means in its second respect to operatively connect the powermeans to said inner teeth to rotate the roller on its axis.

20. In a system for handling objects such as cargo items, wherein thesystem includes support structure of open construction to support theobjects at a support plane,

the combination therewith of:

at least one hollow roller movable bodily through the open supportstructure between a retracted position below said plane and an effectiveposition protruding above the plane to engage the bottoms of the objectsto move the objects across the support structure;

power actuated means extending into the interior of the hollow rollerfrom one end thereof;

remotely controlled means to operatively connect the power actuatedmeans to the roller to shift the roller between its two positions; and

remotely controlled means to operatively connect the power actuatedmeans to the roller to rotate the roller on its axis when the roller isin its effective position.

21. A combination as set forth in claim 20 which includes means insidethe hollow roller to guide the hollow roller on an arcuate path betweenits two positions.

22. In a system for handling objects such as cargo items, wherein thesystem includes support structure of open construction to support theobjects at a support plane,

the combination therewith of:

at least one roller movable bodily in a circular orbit through the opensupport structure between a retracted position below said plane and aneffective position protruding above the plane to engage the bottoms ofthe objects to move theobjects across the support structure with theaxis of the orbit offset from the axis of rotationof the roller;-

power means for the roller; and a control means operable in a firstrespect to cause the power means to shift the roller through one-half ofits orbit between its two positions and operable in a second respect tooperatively connect the power means to the roller to rotate the rolleron its axis when the roller is in its effective position.

23. In a system for handling objects such as cargo items, wherein thesystem includes support structure of open construction to support theobjects at a support plane, I

the combination therewith ofz at least one hollow roller with innercircumferential pear teeth movable bodily through the open supportstructure between a retracted position below said plane and .anefieetive position protruding above the plane to engage the bottoms ofthe objects to move the objects across the support structure;

power means for the roller;

control means operable in a first respect to cause the power means toshift the roller between its two positions and operable .in a secondrespect to operatively connect the power means to the roller to rotatethe roller on its axis when the roller is in its effective position,

drive means extending from the power means into the interior of theroller;

means responsive to the operation of the control means in its firstrespect to cause said drive means to shift the roller between its twopositions;

means responsive to operation of the control means in its second respectto operatively connect the power means to said inner teeth to rotate theroller on its axis;

gearing inside the hollow roller, said gearing including a first gear onthe axis of the orbit and a second gear in mesh both with the first gearand with said inner circumferential teeth of the roller; meansresponsive to operation of said control means in its first respect towalk said second gear around the first gear between a first position anda second position of the second gear to shift the roller between itsretracted position and its effective position; and means responsive tothe operation of the control means in its second respect to rotate thefirst gear while the second gear is in one of its two positions therebyto act through the second gear to rotate 'the roller on its axis.

l t t l l

1. In a cargo handling system for a cargo carrier wherein a plurality ofdistributed support elements support cargo items at a support plane andare rotatable to minimize frictional resistance to movement of the cargoitems along the plane and a plurality of power-actuated rollers areshiftable from lower positions below said plane to upper positionsprotruding above the plane to engage the bottoms of the cargo items tocooperate with the rotatable support elements to move the cargo itemsalong the support plane, the improvement comprising each of said rollersbeing a working part of a corresponding powered unit, said powered unitincluding: an input sun gear; reversible means to actuate the sun gear;a planet gear carrier with its axis of rotation concentric with the sungear; a ring gear unitary with the roller coaxially thereof, said ringgear being rotatably mounted on the carrier with its axis of rotationoffset from the axis of the carrier to cause rotation of the carrier tomove the roller in an orbit between its lower position and its upperposition; planet gear means on the carrier in mesh with both the sungear and the ring gear; and means to rotate the carrier for orbitalmovement of the roller.
 2. An improvement as set forth in claim 1 whichincludes means to releasably immobilize the carrier at the upperposition of the roller.
 3. An improvement as set forth in claim 1 inwhich said ring gear is of cylindrical configuration and is united withthe roller inside the roller; and in which said sun gear, said carrierand said planet gear mEans all extend longitudinally of the rollerinside the roller.
 4. An improvement as set forth in claim 1 in whichsaid planet gear means includes at least one pair of axially spacedcoaxial planet gears.
 5. An improvement as set forth in claim 1 in whichsaid reversible means to actuate the sun gear is a motor; which includesa remote switch to control energization of the motor; and which includesremote means to control the direction of rotation of the motor.
 6. Animprovement as set forth in claim 5 in which said remote switch createsa signal to energize the motor and incorporates means to delayde-energization of the motor when the remote switch is operated.
 7. Animprovement as set forth in claim 1 which includes means to limit thetorque transmitted to the sun gear to a given magnitude above themagnitude of the normal driving torque of the motor but below adestructive magnitude in the event that the movement of a cargo item isblocked while the motor is energized.
 8. An improvement as set forth inclaim 4 which includes reduction gearing to transmit torque to the sungear and in which said torque limiting means is combined with thereduction gearing.
 9. An improvement as set forth in claim 8 in whichthe reduction gearing includes a planetary gear train comprising a sungear, a planet gear carrier, a ring gear and a planet gear on thecarrier in mesh with both the sun gear and the ring gear; and in whichthe torque limiting means frictionally opposes rotation of the ring gearof the reduction gearing.
 10. An improvement as set forth in claim 1which includes means to cause power flow from the sun gear to the planetgear carrier to rotate the planet gear carrier to shift the rollerbetween its lower and upper positions.
 11. An improvement as set forthin claim 10 which includes means responsive to energization of the sungear to latch the carrier in response to movement of the roller to itsupper position and to release the carrier in response to deenergizationof the sun gear to permit the momentum of the rotating parts to rotatethe carrier to shift the roller from its upper position to its lowerposition.
 12. An improvement as set forth in claim 11 which includes asecond latch biased to latch the carrier in response to rotation of thecarrier at the lower position of the roller after the motor isde-energized, said second latch being releasable in response toenergization of the motor.
 13. An improvement as set forth in claim 11which includes a housing enclosing moving parts of the unit; and inwhich the portions of the sun gear and the carrier protrude to theexterior of the housing with the ring gear mounted on the protrudingportion of the carrier and with the roller encasing the ring gear. 14.An improvement as set forth in claim 10 in which the upper portion ofthe housing is of chamfered configuration to minimize head-on impactagainst the housing of cargo items that protrude downwardly from saidplane.
 15. An improvement as set forth in claim 12 which includes guardmeans below said plane adjacent the roller to protect the roller at thelower position of the roller.
 16. An improvement as set forth in claim15 in which the upper portion of the guard means is of chamferedconfiguration to minimize head-on impact against the guard means ofcargo items that protrude downwardly from said plane.
 17. An improvementas set forth in claim 1 in which the floor of the cargo carrier isequipped with seat rails; in which said unit has two longitudinallyspaced means for releasable attaching the unit to a seat raillongitudinally thereof; and in which said unit has two laterally spacedmeans for releasable attachment to a seat rail with the unit positionedtransversely of the seat rail.
 18. In a system for handling objects suchas cargo items, wherein the system includes support structure of openconstruction to support the objects at a support plane, the combinationtherewith of: at lEast one roller movable bodily through the opensupport structure between a retracted position below said plane and aneffective position protruding above the plane to engage the bottoms ofthe objects to move the objects across the support structure; a singledrive means to power the roller; and control means operable in a firstrespect to cause the drive means to shift the roller between its twopositions and operable in a second respect to operatively connect thedrive means to the roller to rotate the roller on its axis when theroller is in its effective position.
 19. A combination as set forth inclaim 18 in which the roller is hollow with inner circumferential gearteeth; in which drive means extends from the power means into theinterior of the roller; which includes means responsive to the operationof the control means in its first respect to cause said drive means toshift the roller between its two positions; and which includes meansresponsive to operation of the control means in its second respect tooperatively connect the power means to said inner teeth to rotate theroller on its axis.
 20. In a system for handling objects such as cargoitems, wherein the system includes support structure of openconstruction to support the objects at a support plane, the combinationtherewith of: at least one hollow roller movable bodily through the opensupport structure between a retracted position below said plane and aneffective position protruding above the plane to engage the bottoms ofthe objects to move the objects across the support structure; poweractuated means extending into the interior of the hollow roller from oneend thereof; remotely controlled means to operatively connect the poweractuated means to the roller to shift the roller between its twopositions; and remotely controlled means to operatively connect thepower actuated means to the roller to rotate the roller on its axis whenthe roller is in its effective position.
 21. A combination as set forthin claim 20 which includes means inside the hollow roller to guide thehollow roller on an arcuate path between its two positions.
 22. In asystem for handling objects such as cargo items, wherein the systemincludes support structure of open construction to support the objectsat a support plane, the combination therewith of: at least one rollermovable bodily in a circular orbit through the open support structurebetween a retracted position below said plane and an effective positionprotruding above the plane to engage the bottoms of the objects to movethe objects across the support structure with the axis of the orbitoffset from the axis of rotation of the roller; power means for theroller; and control means operable in a first respect to cause the powermeans to shift the roller through one-half of its orbit between its twopositions and operable in a second respect to operatively connect thepower means to the roller to rotate the roller on its axis when theroller is in its effective position.
 23. In a system for handlingobjects such as cargo items, wherein the system includes supportstructure of open construction to support the objects at a supportplane, the combination therewith of: at least one hollow roller withinner circumferential pear teeth movable bodily through the open supportstructure between a retracted position below said plane and an effectiveposition protruding above the plane to engage the bottoms of the objectsto move the objects across the support structure; power means for theroller; control means operable in a first respect to cause the powermeans to shift the roller between its two positions and operable in asecond respect to operatively connect the power means to the roller torotate the roller on its axis when the roller is in its effectiveposition, drive means extending from the power means into the interiorof the roller; means responsive to the operatiOn of the control means inits first respect to cause said drive means to shift the roller betweenits two positions; means responsive to operation of the control means inits second respect to operatively connect the power means to said innerteeth to rotate the roller on its axis; gearing inside the hollowroller, said gearing including a first gear on the axis of the orbit anda second gear in mesh both with the first gear and with said innercircumferential teeth of the roller; means responsive to operation ofsaid control means in its first respect to walk said second gear aroundthe first gear between a first position and a second position of thesecond gear to shift the roller between its retracted position and itseffective position; and means responsive to the operation of the controlmeans in its second respect to rotate the first gear while the secondgear is in one of its two positions thereby to act through the secondgear to rotate the roller on its axis.